JP5157131B2 - Heating body and semiconductor manufacturing apparatus equipped with the same - Google Patents

Description

  The present invention relates to a heating body for mounting and heat-treating a wafer, and more particularly to a heating body for heating a wafer having a high temperature rising rate and excellent thermal uniformity.

  Conventionally, in a semiconductor manufacturing process, various processes such as a film forming process and an etching process are performed on a wafer. Examples of semiconductor manufacturing apparatuses that perform processing on such wafers include film forming apparatuses such as CVD and etching, and wafer probers for semiconductor inspection such as coater developers used for wafer photolithography.

  In these semiconductor manufacturing apparatuses, it is necessary to hold and heat the wafer in each processing step. For example, in a photolithography process for forming a resist film pattern on a wafer, the wafer is washed, heated and dried, cooled, and then a resist film is applied to the wafer surface, and the wafer is mounted on a heater in a photolithography processing apparatus. Then, after drying, processing such as exposure and development is performed.

  In this photolithography process, it is necessary to reduce particles generated from a hot plate and other parts. If particles adhere to the wafer, the pattern of that portion cannot be formed, causing a semiconductor chip to fail. Particularly in recent years, since the fine wiring of a semiconductor chip is progressing, it is very important to suppress the generation of particles.

  Further, the wafer processing in these semiconductor manufacturing apparatuses is required to be completed in as short a time as possible in order to improve the throughput. For this reason, the present inventors have studied cooling the heated heater in a short time, and have proposed a semiconductor manufacturing apparatus provided with a cooling means.

  For example, Japanese Patent Application Laid-Open No. 2004-014655 has proposed a semiconductor manufacturing apparatus provided with a cooling block that can be contacted or separated on the surface opposite to the wafer mounting surface of the heater. Japanese Patent Laid-Open No. 2005-150506 discloses a semiconductor manufacturing method in which a cooling liquid flow path is formed in a cooling block to further improve the cooling rate and to maintain the uniformity of the heater temperature from the start of cooling to the end of cooling. A device was proposed.

JP 2004-014655 A JP-A-2005-150506

  As described above, with the progress of miniaturization in recent semiconductors, it is possible to suppress the generation of particles and improve the throughput with respect to the heating element for wafer heating, and to make the temperature distribution of the wafer more uniform. Is required. This thermal uniformity is required not only for the steady state in which the wafer is heated, but also for the transitional state from placing the wafer on the heating body to heating and from heating to cooling.

  In view of such a conventional situation, the present invention suppresses the generation of particles and improves the throughput so that the rate of temperature rise is fast and is excellent not only in a steady state in which a wafer is heat-treated but also in a transient state of wafer processing. It is another object of the present invention to provide a heating body that can achieve soaking properties.

In order to achieve the above object, a heating body for heating a wafer provided by the present invention includes a heater substrate having a wafer mounting surface, and a heater including a heating element provided in contact with the lower surface of the heater substrate , A heat equalizing plate having a higher thermal conductivity than the heater substrate, the heat equalizing plate is fixed to the opposite side of the wafer mounting surface of the heater with a heat insulating layer interposed therebetween, and the material of the heat insulating layer is polyimide, It is one of fluororesin and mica .

  In the heating body of the present invention, in order to suppress generation of particles, the heater substrate is preferably made of ceramics, and particularly preferably aluminum nitride.

  In the heating body of the present invention, it is preferable that the heat capacity of the soaking plate is larger than that of the heater substrate in order to make the temperature distribution of the wafer more uniform. The material of the soaking plate is particularly preferably copper or a copper alloy.

  The present invention further provides an apparatus for heating a semiconductor wafer comprising the above-described heating body of the present invention, and a semiconductor manufacturing apparatus comprising the apparatus for heating a semiconductor wafer. It is.

  ADVANTAGE OF THE INVENTION According to this invention, the heating body with a quick temperature increase rate and excellent heat uniformity can be provided by attaching a heat equalization board to a heater via a heat insulation layer. Therefore, by applying the heating body of the present invention to a semiconductor manufacturing apparatus, not only the generation of particles can be suppressed, but also the throughput can be improved. Further, not only in the steady state in which the wafer is heated, but also in the wafer processing. Excellent thermal uniformity can be achieved even in a transient state.

  For example, as shown in FIG. 1, the heating body of the present invention includes a heater 1 in which a heating element 3 is provided on a heater substrate 2, a heat insulating layer 4, and a soaking plate 5. It is fixed to the surface opposite to the wafer mounting surface 1 a via a heat insulating layer 4. Since the heat conductivity of the soaking plate 5 is set higher than that of the heater substrate 2, the heat generated by the heating element 3 can be spread evenly over the entire surface of the heater 1. As a result, the heat uniformity of the wafer mounting surface 1a of the heater 1 is greatly improved as compared with the case where the heat equalizing plate 5 is not provided.

  However, when the soaking plate 5 is directly attached to the heater 1 without the heat insulating layer 4, the heating rate is lowered due to the heat capacity of the soaking plate 5 when the heater 1 is heated by the heating element 3. Inevitable. On the other hand, by attaching the heat insulating layer 4 between the heater 1 and the soaking plate 5, the amount of heat generated by the heating element 3 taken away by the soaking plate 5 is reduced. It is possible to increase the heating rate.

  As shown in FIG. 1, the heater 1 used in the present invention is composed of a heater substrate 2 provided with a heating element 3, and one surface thereof (opposite to the surface on which the heat insulating layer 4 and the soaking plate 5 are fixed). Side surface) is a wafer mounting surface 1a. There is no restriction | limiting in particular as a material of a heater board | substrate, The metal heater board | substrate conventionally used and the ceramic heater board | substrate can be used. A composite of metal and ceramic, such as Cu-W, Si-SiC, Al-SiC, or the like can also be suitably used.

  Particularly in recent years, it has been required to suppress the generation of particles for a heating body on which a wafer is placed. For this reason, among the materials for the heater substrate described above, ceramics is preferable because it generates less particles. Preferred ceramics include silicon carbide, silicon nitride, aluminum nitride, alumina, mullite, and composites thereof. In particular, silicon carbide and aluminum nitride are preferable because of high thermal conductivity and a uniform temperature distribution on the wafer mounting surface. If the material has a thermal conductivity of 100 W / mK or more, a heater with excellent heat uniformity can be obtained.

  The heating element provided in the heater may be a conventionally used material, for example, W, Mo, stainless steel, nichrome, etc., and may be embedded in the heater substrate or opposite the wafer mounting surface of the heater substrate. You may install in the side surface. These heating elements can be formed on the substrate in a predetermined pattern by a technique such as printing, or a coil or metal foil formed in a predetermined pattern by etching. When the heating element is a coil or a metal foil, it can be fixed to the substrate by a mechanical method such as screwing. In addition, as a method of embedding the heating element in the substrate, for example, the above-described coil or metal foil is sandwiched between two substrates and stacked, or a substrate on which the heating element is formed by printing or the like is used for another substrate. It can be embedded by overlapping with the substrate.

  When the heater substrate is a conductor, it is attached to the heater substrate after ensuring insulation by sandwiching the heating element with an insulator. The insulator that sandwiches the heating element is not particularly limited as long as it is a heat-resistant insulator. For example, mica, silicon resin, epoxy resin, phenol resin, or the like can be used. In addition, when the heating element is sandwiched between insulating resins, the filler can be dispersed in the resin in order to increase the thermal conductivity of the resin and smoothly transmit the heat generated in the heating element to the heater. The filler material is not particularly limited as long as it does not react with the resin, and examples thereof include boron nitride, aluminum nitride, alumina, and silica.

  The material of the heat insulating layer attached between the heater and the soaking plate is not particularly limited as long as it has a lower thermal conductivity than the heater substrate and is excellent in heat resistance. Specifically, mica, silicon resin, epoxy resin, phenol resin, polyimide resin, and the like can be given. Moreover, what has deformability, such as a foam metal, can also be used. These heat insulation layers have the effect of further increasing the temperature increase rate of the heater by reducing the amount of heat transmitted to the soaking plate among the heat generated by the heater.

  The soaking plate attached to the heater via the heat insulating layer needs to have higher thermal conductivity than the heater. Examples of the material of the soaking plate include metals such as copper and aluminum or alloys thereof, ceramics, and composites of ceramics and metals. Among these, copper having a high thermal conductivity or an alloy thereof is particularly suitable. By installing these soaking plates made of a material having a high thermal conductivity, the temperature distribution on the wafer mounting surface of the heater can be made more uniform.

  That is, when the temperature of the heater is raised, the heat transfer to the soaking plate is poor because of the presence of the heat insulation layer, and the heating rate of the heater cannot be followed, so the influence of the soaking plate is relatively small. . However, even if a small amount of heat is transferred to the heat equalizing plate through the heat insulating layer, the temperature inside the heat equalizing plate is heated uniformly. Therefore, the temperature distribution on the wafer mounting surface of the heater existing through the heat insulating layer is reduced. It can improve in the direction which becomes more uniform. Of course, even in a transient state of wafer processing, a heat equalizing plate having a temperature distribution lower than that of the heater and having a uniform temperature distribution is present on the back surface side of the heater. Since generation | occurrence | production etc. can be suppressed, a wafer mounting surface becomes more uniform temperature distribution.

  Further, by making the heat capacity of the heat equalizing plate larger than that of the heater substrate, the temperature distribution of the heat equalizing plate itself is likely to be uniform, so that a more uniform temperature distribution on the wafer mounting surface can be realized. Furthermore, by using a heat equalizing plate with a larger heat capacity than the heater substrate, the heat capacity of the heater substrate becomes relatively small, so that the rate of temperature rise can be increased, achieving high temperature rise and high temperature uniformity at the same time. can do.

  There are no particular restrictions on the method of attaching the heat insulating layer and the heat equalizing plate to the heater, and mechanical methods such as screwing can be used in addition to methods such as brazing and joining. Although depending on the thermal expansion coefficient of each material of the heat equalizing plate, the heat insulating layer, and the heater substrate, since these materials generally have different thermal expansion coefficients, a structure that is fixed by a mechanical method such as screwing is preferable. As a mechanical fixing method, for example, a female screw hole is formed on the surface of the heater substrate opposite to the wafer mounting surface, a through hole larger than the screw diameter is formed in the heat equalizing plate, and a bolt is inserted. There is a way to fix it. In this case, by increasing the diameter of the screw hole of the heat equalizing plate, it is possible to absorb the expansion difference due to the temperatures of the heat equalizing plate, the heater, and the heat insulating layer and the dimensional difference due to the thermal expansion coefficient.

  In the heating body of the present invention, for example, as shown in FIG. 1, a cooling module 6 can be disposed below the soaking plate 5 on the side opposite to the heater 1. When it becomes necessary to cool the heat equalizing plate or heater, the cooling module abuts the back surface of the heat equalizing plate from the opposite side of the wafer mounting surface and removes the heat, thereby quickly Can be cooled to. Further, since the temperature can be increased efficiently by separating the heater from the soaking plate when the heater is heated, the cooling module is preferably movable. As a method for making the cooling module movable, lifting means such as an air cylinder is used. By installing the cooling module in this way, the cooling rate of the heater can be greatly improved and the throughput can be improved.

  Further, when priority is given to the cooling rate of the heater, the cooling module may be fixed to the soaking plate of the heating body. In the case of this structure, since the heater and the cooling module are fixed via a soaking plate or the like, the cooling rate can be increased compared to the case where the cooling module is movable. As a method for fixing the cooling module, it can be fixed by a mechanical method such as screwing as in the case of fixing the soaking plate and the heater. In addition, when fixing the heater, heat equalizing plate, and cooling module with screws, the number of screws is set to 3 or more, and further 6 or more, so that the adhesion of each part is increased and the cooling capacity of the heater is further improved. It is preferable because it improves.

  The material of the cooling module is not particularly limited, but aluminum, copper and alloys thereof are particularly preferably used because of their relatively high thermal conductivity. Also, stainless steel, magnesium alloy, nickel, and other metal materials can be used. Furthermore, in order to impart oxidation resistance to the cooling module, a metal film having oxidation resistance such as nickel, gold, or silver can be formed on the surface using a technique such as plating or thermal spraying. Among these, aluminum plated nickel and copper plated nickel are excellent in oxidation resistance, have high thermal conductivity, and are relatively inexpensive. preferable.

  Ceramics can also be used as the material for the cooling module. The ceramic in this case is not particularly limited, but aluminum nitride and silicon carbide are preferable because they have a relatively high thermal conductivity and can quickly take heat away. Silicon nitride and aluminum oxynitride are preferable because of high mechanical strength and excellent durability. Furthermore, oxide ceramics such as alumina, cordierite, and steatite are preferable because they are relatively inexpensive. Thus, since the material of a cooling module can be selected variously, what is necessary is just to select a material according to a use.

  It is also possible to flow a coolant through the cooling module. By flowing the refrigerant, the heat transferred from the heating body to the cooling module can be quickly removed, so that the cooling rate of the heating body can be further improved. As the refrigerant flowing in the cooling module, water, liquid such as fluorinate, gas such as nitrogen and air can be selected, and there is no particular limitation, but water is most preferable in consideration of the specific heat, price, and the like.

  In addition, when fixing a cooling module to the soaking | uniform-heating board of a heating body, it is also possible to heat up, without flowing a refrigerant | coolant to a cooling module. In this case, since the refrigerant does not flow in the cooling module, the heat generated by the heating element is not lost to the refrigerant and escapes out of the system, and more efficient temperature rise is possible. However, even in this case, efficient cooling is possible by flowing the refrigerant through the cooling module during cooling.

  As a preferable example of the cooling module having a flow path for the refrigerant, two aluminum plates are prepared, and a flow path for flowing the refrigerant to one aluminum plate is formed by machining or the like. Laminate aluminum plates. These aluminum plates are preferably nickel-plated over the entire surface in order to improve corrosion resistance and oxidation resistance. Further, in order to prevent a refrigerant such as water from leaking, for example, an O-ring or the like is inserted around the flow path, and then two aluminum plates are bonded together by screwing or welding.

  Alternatively, as another preferred embodiment, two copper (oxygen-free copper) plates are prepared, and a flow path is formed in one copper plate by machining or the like. It can also be brazed and joined together with the stainless steel pipe serving as the doorway. The produced cooling module is preferably nickel-plated over the entire surface in order to improve corrosion resistance and oxidation resistance.

  Furthermore, as another form, it can also be set as a cooling module by attaching the pipe | tube which flows a refrigerant | coolant to the single side | surface of cooling plates, such as an aluminum plate or a copper plate. In this case, it is possible to increase the cooling efficiency by forming a counterbored groove having a shape close to the cross-sectional shape of the pipe in the cooling plate, and bringing the pipe into close contact with the groove. Moreover, in order to improve the adhesiveness of a cooling pipe and a cooling plate, you may insert thermally conductive resin, ceramics, etc. as an intervening layer between both.

  The heating body of the present invention described above is particularly suitable as a heating body for semiconductor heating that requires a high temperature rising rate as well as excellent soaking. Therefore, for example, as shown in FIG. 1, the heating body of the present invention including the heater 1, the heat insulating layer 4, and the soaking plate 5 is accommodated in a container 7 together with a cooling module 6 as necessary. An apparatus for heating a semiconductor wafer can be configured.

  The semiconductor manufacturing apparatus provided with this semiconductor wafer heating apparatus can make the temperature distribution of the wafer to be processed more uniform. Therefore, for example, in a film forming apparatus such as CVD, the thickness of the film can be made uniform, and in an apparatus such as a coater developer, the accuracy of patterns such as wiring can be improved. Further, in an inspection apparatus such as a wafer prober, since the temperature distribution is excellent, a good wafer inspection can be performed. Further, since the temperature rise rate is also excellent, throughput can be improved and wafer processing can be performed in a shorter time.

  As a specific example of the heating body according to the present invention, a heating body comprising a heater substrate made of various materials, a heat insulating layer, and a soaking plate was constructed, and its temperature rising / falling characteristics and soaking properties were evaluated. In addition, each physical property value (thermal conductivity, specific heat, specific gravity) of the materials used as the heater substrate, the heat insulating layer, and the soaking plate is as shown in Table 1 below.

[Example 1]
A heater substrate was prepared from each material shown in Table 2 below, the diameter was set to 320 mm, and the thickness was changed as shown in Table 2. A heating element having a predetermined pattern formed by etching stainless steel foil (thickness 0.05 mm) was attached to these heater substrates to obtain heaters. Mica having a thickness of 0.5 mm and a soaking plate shown in the following Table 2 were sequentially attached to the heating element side of each heater obtained, and the whole was fixed by bolting to produce a heating element. In addition, a cooling module prepared by bonding copper plates on which flow paths were formed by brazing was prepared.

  Power is supplied to the heating element and heated to 180 ° C., the time until the heating body reaches 180 ° C. is measured, and the wafer is mounted on the mounting surface 1 minute after reaching 180 ° C. The temperature distribution of the wafer (thermal uniformity at 180 ° C.) was measured with a 17-point wafer thermometer (resistance temperature detector). In addition, after the wafer is removed, the cooling module is brought into close contact with the back side of the heating body to cool it from 180 ° C. to 150 ° C., and the time until it reaches 150 ° C. is measured. A wafer was mounted later, and the temperature distribution (heat uniformity at 150 ° C.) of the wafer after 1 minute was measured in the same manner as described above. The obtained results are shown in Table 2 below.

  From the results of Table 2 above, although the heater substrate is made of a Cu plate having a thickness of 10 mm and has no soaking plate, the heating body is excellent in soaking properties, but the present invention combines the AlN heater substrate, the heat insulating layer, and the soaking plate. It can be seen that the rate of temperature increase and the rate of temperature decrease is very slow as compared with the heating body. In addition, it can be seen that a heating element comprising an AlN heater substrate and a heat insulating layer and having no soaking plate has poor soaking properties compared to those having a soaking plate. Furthermore, it can be seen that when the heat capacity of the soaking plate is larger than that of the AlN substrate, the heating rate is very fast and the soaking property is excellent.

  A heating element was prepared in the same manner as described above, but a heater in which a stainless steel foil heating element was embedded in an AlN heater substrate was used. About each obtained heating body, the test similar to the above was done and soaking | uniform-heating property, the temperature increase rate, and the temperature-fall rate were evaluated. For comparison, a heating body that does not use a heat insulating layer was also evaluated. The obtained results are shown in Table 3 below. It can be seen that the heating element without the heat insulating layer has a very slow temperature increase rate compared to other heating elements.

[Example 2]
Although the heating body was produced similarly to the said Example 1, as shown in following Table 4 as a soaking plate, Al or Cu-W was used. About each obtained heating body, the test similar to the above was done and soaking | uniform-heating property, the temperature increase rate, and the temperature-fall rate were evaluated. The results obtained are shown in Table 4 below. From the results of Table 4 below, it can be seen that the temperature rise characteristic is superior when the heat capacity of the soaking plate is larger than the heat capacity of the heater substrate.

[Example 3]
As a heater substrate, Si—SiC or Al—SiC shown in Table 5 below was used, the diameter was changed to 320 mm, and the thickness was changed as shown in Table 5. Since these heater substrates have conductivity, a polyimide film having a thickness of 0.1 mm is pasted on the opposite side of the wafer mounting surface, and a stainless steel foil is used as a heating element in the same manner as in the first embodiment, and a heat insulating layer. Heating bodies were prepared using 0.2 mm thick polyimide films and Cu plates with the thicknesses shown in Table 5 as the soaking plates.

  About each obtained heating body, the test similar to the above was done and soaking | uniform-heating property, the temperature increase rate, and the temperature-fall rate were evaluated. The obtained results are shown in Table 5 below. As can be seen from the results in Table 5 below, the temperature rise characteristic is superior when the heat capacity of the soaking plate is larger than the heat capacity of the heater substrate.

It is a schematic sectional drawing which shows one specific example of the heating body by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heater 1a Wafer mounting surface 2 Heater board 3 Heat generating body 4 Heat insulation layer 5 Heat equalizing plate 6 Cooling module 7 Container

Claims (7)

A heating body for heating a wafer, comprising a heater substrate having a wafer mounting surface, a heater provided in contact with the lower surface of the heater substrate, and a heater having a higher thermal conductivity than the heater substrate. A heat plate, and the heat equalizing plate is fixed to the opposite side of the wafer mounting surface of the heater via a heat insulating layer, and the material of the heat insulating layer is any one of polyimide, fluororesin, and mica. Heating body.   The heating body according to claim 1, wherein a material of the heater substrate is ceramics.   The heating body according to claim 2, wherein the heater substrate is made of aluminum nitride.   The heating body according to any one of claims 1 to 3, wherein a heat capacity of the soaking plate is larger than that of the heater substrate.   The heating body according to any one of claims 1 to 4, wherein a material of the soaking plate is copper or a copper alloy.   An apparatus for heating a semiconductor wafer comprising the heating body according to claim 1.   A semiconductor manufacturing apparatus comprising the apparatus for heating a semiconductor wafer according to claim 6.

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